Abeam of electrons (with unspecified energy) is partially transmitted through a thin ti foil a) from a reliable source, find the mass density (at room temp.) and molar mass of this element. calculate the density of atoms n (in atoms/cm3, or just cm) d. b) for a foil of thickness t-72 nm , the transmitted electron beam has 43% of the incident-beam intensity. determine the mean free path length л (in nm) for scattering in in (at this energy). c) determine the total atomic scattering cross section o, for an atom at this energy. use appropriate units

okay i have so many questions. but the big one here is: um wt..f is this mess? ?

electrical power

it's when something is going so fast it makes a loud noise, breaking the sound barrier, for example: a jet makes a loud noise, not only cause of the jet but because they reached a point where they went so fast that you can year the noise from various parts, kinda like a police car, lets say the car was going   so fast that you hear the siren of the cop car right next to you, but the car is probably a mile a way, it's cos the siren was next to you a few seconds if you understand me